1. Field of the Invention
The present invention relates generally to a shunt member for a decorative lamp unit, and more particularly to a shunt member including a first lead wire, a second lead wire, and a shunt wire wound between the first lead wire and the second lead wire.
2. Description of the Prior Art
Decorative light strings are commonly used in celebrations and festivals. The light string usually comprises a number of lamp holders connected in series to an electric wire. Bulbs, usually incandescent ones, are mounted to the lamp holders for connection with the wires. When a single lamp fails to illuminate, the whole string fails to light. It is very time-consuming to locate and replace the defective bulb. Thus, light strings with shunt circuits for overcoming the problems are known, such as U.S. Pat. Nos. 6,084,357 and 6,323,597 B1. These conventional designs of shunt circuits, however, require a shunt member to be encased in the lamp itself or are made with expensive electrical elements. The manufacturing process is also complicated.
To overcome the problems of the prior art, a filament shunt member adapted to be mounted in the lamp holder is designed in a co-pending application. The shunt member mainly includes a core made of alumina surrounded by an insulation sheath and has two ends electrically engaging a first contact and a second contact mounted in the lamp holder. When any of the lamps malfunctions, such as burning out, electrical current is capable of flowing through the shunt member to keep the other light lamps of the light string lighting. However, it is noted that a proper electric resistance of the alumina core depends on perfect surface of the alumina core. So, the shunt member should be inserted into the lamp holder very carefully. Otherwise, the surface of the alumina core is easy to be scraped, resulting in improper resistance.
Thus, it is desired to have an improved shunt member to overcome the problem.
Consequently, a primary object of the present invention is to provide a shunt member for a decorative lamp unit. The shunt member is mounted in the lamp holder of the decorative lamp unit and electrically connected with the filament of the lamp in parallel.
The other object of the present invention is to provide a shunt member comprising an insulation sheath, a pair of lead wires spaced from each other, and a shunt wire. The lead wires are extended from the insulation sheath and engage with the contacts of the lamp holder. The shunt wire is wound between the lead wires, so that the surface of the shunt wire will not be scraped by the contacts of the lamp holder.
The other object of the present invention is to provide a light string having a shunt circuit for each lamp of the light string to avoid defective lamps causing malfunction of the whole light string.
To achieve the above objects, in accordance with the present invention, there is provided a shunt member for a light bulb, which includes an insulation sheath, a first lead wire having a shunt wire engaging section located in the insulation sheath, a second lead wire having a shunt wire engaging section located in the insulation sheath and adjacent to the shunt wire engaging section of the first lead wire. A shunt wire is connected between the shunt wire engaging sections of the first lead wire and the second lead wire for forming a shunt circuit of the bulb.